In a conventional printer, original image data (RGB data or the like) scanned by a scanner or externally inputted is stored into memory by using a technique of compressing original image data because this technique needs smaller amounts of memory space used. Compressed image data is printed (image-reproduced) in the following manner: the compressed image data is decompressed, the decompressed data is converted into CMYK data, and the CMYK data is outputted to the print engine.
Japanese Laid-Open Patent Application No. 2003/162382 (Tokukai 2003-162382; published on Jun. 6, 2003) uses a lossy compression technique that achieves a high data compression ratio. Incidentally, image data decompressed after it was lossy-compressed usually has distortion from original image data. Therefore, there is a low reliability or faithfulness in image reproduction. This is because image segmentation is performed on the basis of decompressed image data (CMYK data), which gives a low accuracy in judgment for image segmentation.
In view of this, Japanese Laid-Open Patent Application No. 2003/162382 performs, for realization of high-quality image processing, image segmentation on yet-to-be-lossy-compressed original image data, generates a segmentation signal (image segmentation data), and stores it into memory (image segmentation memory). Then, after lossy-compressed data is decompressed, correction is performed on decompressed image data (CMYK data) in accordance with the segmentation signal.
However, Japanese Laid-Open Patent Application No. 2003/162382 causes the problems of requiring increase of the image segmentation memory space when the size of the segmentation signal is large in size and of taking much time for data transmission.